1. Field of the Invention
This invention relates to a silicone rubber composition which has low swelling properties in a variety of solvents.
2. Description of the Prior Art
Silicone rubbers are excellent in electrical insulating property, heat resistance, cold resistance, weatherability, etc. and are used in various fields. However, the silicone rubbers are poor in solvent resistance. For example, upon making contact with or being immersed in a solvent, a silicone rubber swells to be deformed markedly and reduced in strength.
In order to improve the solvent resistance of the silicone rubbers, fluorosilicone rubbers containing a fluoroalkyl group such as 3,3,3-trifluoropropyl have been developed.
The fluorosilicone rubbers exhibit excellent resistance to nonpolar solvents such as benzene, but they are yet poor in resistance to polar solvents such as ketones, esters, etc. In fact, the fluorosilicone rubbers will swell extremely easily in polar solvents.